LEA index range consistent with SCO

Using the index step factor to have a consistent index range of 15 steps
when having a voice call stream over LE audio and SCO

Flag: com.android.media.audio.equal_sco_lea_vc_index_range
Test: manual
Bug: 364364777
Change-Id: I84e711f46463b256581b8b01332fb0bcab624d4b